This invention relates generally to the manufacture of semiconductor integrated circuits.
It is generally desirable to transfer a pattern repeatedly to a semiconductor wafer in the course of semiconductor manufacturing. Conventionally, this is done using processes involving lithography and etching. However, lithography and etching may tend to be relatively expensive and are limited in their resolution or throughput. Thus, there has been a demand for better ways to transfer patterns repeatedly to semiconductor wafers.
One such technique is called laser-assisted direct imprint (LADI). In this process, a pattern is formed on a quartz mold and the quartz mold with the pattern is pressed against a silicon substrate. An excimer laser irradiates the quartz mold. Due to the irradiation of the quartz mold, the upper surface of the silicon substrate is melted. As a result, the pattern on the mold is transferred to the molten silicon over a relatively short time period, generally less than 250 nanoseconds. After the silicon has solidified, the mold and substrate are separated.
LADI has been used to transfer patterns to structures with resolutions better than 10 nanometers. See Chou, Stephen Y., Keimel, Chris, and Gu, Jian, xe2x80x9cUltrafast and direct imprint of nanostructures in silicon,xe2x80x9d Nature, 835-837 (2002).
While the techniques of laser-assisted direct imprint show considerable promise, there is still a need for better ways to transfer the pattern to the molten silicon.